2024-02-23
Motivation. The Rice’s whale (Balaenoptera ricei) is endangered with an estimated population size of 51 individuals (Garrison et al. 2020). The Biological Opinion (NOAA 2020) that proposes vessel mitigation measures is based on a distribution model (Roberts et al. 2016) that has been superseded by a newer model (Litz et al. 2022) showing range expansion into the western Gulf of Mexico.
Methods. We adhered to similar methods as in the Biological Opinion (NOAA 2020) for creating a new Whale Area also based on the 100- to 400- meter isobaths to now extend to the western Gulf of Mexico, except without a 10 km buffer (since only marginal improvement from 94% to 97% containment of distribution). Risk to ship strike was based on the same AIS vessel traffic data (2014-2018).
| Item | # | % |
|---|---|---|
| Whales in Study (U.S. Gulf of Mexico) | 51 | 100% |
| Whales in Original Whale Area (NMFS, 2020) | 27 | 52% |
| Whales in New Whale Area | 48 | 94% |
\[ Risk = {Whale\:density}\:(\#/100km^2) * {Vessel\:traffic\:(km/100km^2)} \]
| Speed - Vessel Type | Risk Reduction by Whale Area | |||
|---|---|---|---|---|
| Original | % | New | % | |
| All speeds - All vessels | 11,072 | 12% | 84,667 | 93% |
| All speeds - Oil & Gas vessels | 2,010 | 2% | 32,911 | 36% |
| > 10 knots - All vessels | 8,196 | 11% | 66,952 | 93% |
| > 10 knots - Oil & Gas vessels | 695 | 1% | 21,001 | 29% |
This report received funding from Earthjustice and NRDC. The AIS data used in (NMFS 2020) were provided by NMFS pursuant to a Freedom of Information Act request. A portion of the background section was contributed by Jay Barlow. Steve Mashuda (Earthjustice) and Michael Jasny (NRDC) reviewed drafts of the report.